Selective Targeting of c-Abl via a Cryptic Mitochondrial Targeting Signal Activated by Cellular Redox Status in Leukemic and Breast Cancer Cells

• Published in: Pharmaceutical research 2012-08, Vol.29 (8), p.2317-2328
• Main Authors: Constance, Jonathan E., Despres, Samuel D., Nishida, Akemi, Lim, Carol S.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Apoptosis; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Cancer; Cell Death; Cell Line, Tumor; Cercopithecus aethiops; COS Cells; Female; Gene Expression; General pharmacology; Humans; Kinases; Leukemia - genetics; Leukemia - metabolism; Leukemia - pathology; Mammary Neoplasms, Animal - genetics; Mammary Neoplasms, Animal - metabolism; Mammary Neoplasms, Animal - pathology; Medical Law; Medical sciences; Mice; Mitochondria; Mitochondria - genetics; Mitochondria - metabolism; Mitochondria - pathology; Molecular Sequence Data; Oxidative Stress; Pharmaceutical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Pharmacology/Toxicology; Pharmacy; Protein Transport; Proto-Oncogene Proteins c-abl - analysis; Proto-Oncogene Proteins c-abl - genetics; Proto-Oncogene Proteins c-abl - metabolism; Reactive Oxygen Species - metabolism; Recombinant Fusion Proteins - analysis; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Research Paper
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1007/s11095-012-0758-9

Purpose The tyrosine kinase c-Abl localizes to the mitochondria under cell stress conditions and promotes apoptosis. However, c-Abl has not been directly targeted to the mitochondria. Fusing c-Abl to a mitochondrial translocation signal (MTS) that is activated by reactive oxygen species (ROS) will selectively target the mitochondria of cancer cells exhibiting an elevated ROS phenotype. Mitochondrially targeted c-Abl will thereby induce malignant cell death. Methods Confocal microscopy was used to determine mitochondrial colocalization of ectopically expressed c-Abl-EGFP/cMTS fusion across three cell lines (K562, Cos-7, and 1471.1) with varying levels of basal (and pharmacologically modulated) ROS. ROS were quantified by indicator dye assay. The functional consequences of mitochondrial c-Abl were assessed by DNA accessibility to 7-AAD using flow cytometry. Results The cMTS and cMTS/c-Abl fusions colocalized to the mitochondria in leukemic (K562) and breast (1471.1) cancer phenotypes (but not Cos-7 fibroblasts) in a ROS and PKC dependent manner. Conclusions We confirm and extend oxidative stress activated translocation of the cMTS by demonstrating that the cMTS and Abl/cMTS fusion selectively target the mitochondria of K562 leukemia and mammary adenocarcinoma 1471.1 cells. c-Abl induced K562 leukemia cell death when targeted to the matrix but not the outer membrane of the mitochondria.